Ice making method



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United States Patent 2,833,126 ICE' MAKING METHoD` Glenn Mutiiy, Springfield, Ohio Original application November 14, 1950, Serial No. 195,664, n'ow Patent No. 2,695,502, dated November 30, 1954. Divided and this application January 19, 1954, Serial No. 404,985

f 1 (iaim. (CLIM-172) This application is a division of my copending United States application Serial Number 195,664, filed November 14, 1950, now Patent No. 2,695,502, issued November 30, 1954, which includes a further development of the ice making apparatus shown in my copending United States application Serial No. 174,944 tiled .Tuly 20, 1950. The last mentioned patent application refers in particular to commercial ice making equipment and the present application to an ice maker adapted for use in a household refrigerator of either the compression or absorption type. It is noted, however, that application Serial Number 174,944, now Patent No. 2,774,223, issued December 18, 1956, includes features adapted for use in household refrigerators and the present application will be useful in commercial as well as household refrigerators although here illustrated in connection with a household refrigerator.

Reference is also made to my United States Patents No. 2,145,775 issued January 21, 1939; No. 2,291,826 issued August 4, 1942; and No. 2,359,780 issued October 1-0, 1944 for earlier disclosures of apparatus for lifting ice from the water in which it has been formed, for storing the ice above the water level and for draining the water of meltage from the ice back to the ice maker tank. Reference is also made to my copending United States applications Serial No. y50,101 filed September 20, 1948, now Patent No. 2,672,016, issued March 16, 1954, and Serial No. 109,942 tiled August 12, 1949, now Patent No. 2,672,017, issued March 16, 1954, and to my Canadian patent application Serial No. 588,997 tiled lune 13, 1949.

In some of the above mentioned earlier applications of mine, I have disclosed the use of a water pump to circulate water through the ice maker tank'or over the surfaces upon which icc is being frozen. I have also shown the method of oating ice from the tank in which it has been formed, apparatus forvmechanically lifting the ice from the tank andthe method of pushing a round disk of ice from the tank by means of the head of water accumulated back of it when the ice disk blocks the overflow passage leading from the tank.

One of the objects of the present invention is to eliminate the need for a water pump with its attendant requirement of a packing gland or a Vertical drive shaft, and still make clear ice.

Another object is to utilize the elevator which lifts the ice from the water for the additional purpose of agitating the water so as to maintain a constant flow of water over the surfaces of the ice as it forms.

A further object is to reduce the power requirement for agitating the water and lifting the ice.

An additional `object is to p rovide positive means for rolling ice disks into the ice storage compartment instead of employing water flow to float them from the tank in which they are formed or to use a head of water to push them out. s

Another object is to provide'means for lifting-the ice disks from the water in a'tmanner to drain water from rice them more completely before they drop into the ice bunker.

Still another object is to accomplish the ice lifting and water agitation with a motor requiring an electrical input more nearly balancing the number of B. t. u.s per hour required to maintain a butter compartment at the optimum temperature when located within the food storage vcompartment of a household refrigerator.

A still further object is to conserve the space within the refrigerator by a more compact arrangement of parts and by utilizing a part of the space `for the dual purpose of storing ice andl for storing excess-water in the event that all of the stored ice is accidentally melted.

An additional object isto control air temperature within the main food compartment by means of a thermostatic expansion valve mainly responsive to changes of air temperature Iand thereby to regulate the proportional cooling of the icemaker evaporator and the air cooling evaporator.

Anotheryobject is to employ the two evaporators above mentioned as a secondary system which operates during idle periods of the compressor to transfer heat from `cabinet air to the ice-maker tank.

A further object is to cause the ilow diverting valveto serve the additional purpose of aiding in the defrosting of the freezer evaporator and providing for pressure re# lief from the evaporator being defrosted.

In the drawings:

Figure l is a side elevation of the upper portion of a household refrigerator showing the ice-making apparatus' partly in section.

Figure 2 is a front View of Figure 1 showing the same' apparatus.

Figure 3 is a horizontal sectional view of Figure 1 or Figure 2 taken on the line 3 3 thereof, omitting the belt.

Figure 4 is a front elevation of the upper portion of a` refrigerator showing a modified 'arrangement in which ice is rolled out of the ice-maker tank and stored in a separate ice bunker.

Figure 5 is a plan view of the apparatus seen in Fig-k ure 4.

Figure 6 is a diagrammatic View showing a refrigeration system suitable for use in connection with views.

Referring now to Figure l, we see that the refrigerator cabinet 10 encloses an ice-maker tank 12 in which ice is fro-zen by the method disclosed in my previous patentsV and copending applications and particularly shown in my United States application Serial No. 174,944 wherein two disks of ice separately started are caused to freeze together to make a thicker disk which is then released to float and is pushed from the tank by the head of water back of it. 1n the present Figure 1, it will be seen that the ice disks 14 are engaged by the vanes 16 which vare attached to or formed integrally with the belt 18. This belt is driven' by a pulley 20 and runs over the idler pulley 22 which is located adjacent to the normal operating water level 24 in the tank 12. This belt passes through the widerupper' tank 26 in a space 28 provided in the rear portion thereof and divided from the main tank 26 by means of the walls 30 and 32. The rear end wall 34 of the ice-maker tank 12 is joined with the rear wall of the upper tank 26 in the same plane so that these rear Walls form one continuous surface which prevents the ice disks 14 from rolling off of the vanes 16 as the belt A18 carries them upwardly to the position of the ice disk 14 which is about to roll olf of the belt into the ice bunker formed by the upper tank 26.

The pulley 20 is driven at a suitable speed to drive the belt at such linear velocity that the Vanes 16 enter and l leave the water in the ice-maker tank 12 without objectional splashing or noise and yet fast enough to produce a the previous 2,833,126 y Y Y e f, c) substantial lcirculation of water within the ice-maker tank 12 in a counter-clockwise direction as viewed in Figure 1. This circulation of Water washes air bubbles from the sur faces of ice disks 14 in process of formation and also carries any floating `ice disks to the left as viewed in Figure l so that they come into engagement with the varies 16 of the belt Y18pand are finally lifted by this belt to be deposited in the ice bunker 26. The vanes 16 are preferably solid paddles and their width is nearly as great as that of the ice maker tank 12 so that they produce the maximum movement of water. Assuming the ice disks to be one inch thick, the width of the vanes 16 will be only slightly less than one inch while their length measured radially from one of the pulleys as the vane passes `over it is preferably such as to extend from the belt Aa distance somewhat greater than one-half the diameter of an ice disk. Since the vertical channel formed by the two side walls 30the wall 34 and the belt is only slightly wider than the thickness of the ice disks, they cannot fall off of the vanes 16 during their upward travel. The ice disks must, however, fall off of the belt as it passes over the upper pulley 20 and they can only fall into the ice bunker 26.

Screens, gratings, or removable sheets 36 and 38 separate the upper tank 26 and the lower tank 12. This prevents ice disks from returning to the ice-maker tank from the ice bunker and also provides that any water of rneltage from ice stored in the bunker `will ow back to the icemaker tank 12.

One of the important features of this invention is the fact that the ice bunker 26 is located above the ice-makin g tank and provided with vertical `walls which are joined in a water-tight manner to the top of the ice-maker tank, while the access door 40 is located at the upper front portion of the tank, allowing the water-tight front wall of tank 26 to extend upwardly to the opening closed by this door. This provides a water-tight compartment extending upwardly from the ice making tank 12 and having suff1- cient internal volume to hold more water than would be obtained by `melting the lmaximumsupply of ice that can be stored in the bunker 26. This provides against flooding the refrigerator and the floor of the room in which it is located in the event of accidental stoppage such as might be caused by failure of electrical current or of a vital part of the refrigeration system.

In the event that such a failure occurs and operation is re-established while the upper tank contains the water of meltage, no harm will result and the first ice disks formed will fall into the Water which now lls the lower portion of the ice bunker. The first of this ice will melt to aid in cooling the water, but as ice begins to accumulate in the bunker, the water level will drop until it will eventually stabilize at the normal water level 24 within the ice-maker tank 12. Assuming now that some of the ice is removed from the bunker and the ice maker continues to operate,

using up some of the water in the tank 12 `by converting it into ice, thewater level 24 will fall and with it the lloat 42 which causes the water inlet valve 44 to open and restore the operating level to the line 24. The `same replenishment of water within the tank 12 occurs when water is drawn from the faucet 46.

Figure 2 shows a front view of Figure l, including the motor 48 and its speed reduction gearing 50 which drives the shaft 52 upon which the driving pulley 20 is mounted. Due to the light load imposed by the pulleys and belt plus the occasional lifting of an ice disk and the fact that the gearing 50 provides a considerable ratio of speed reduction, the motor 48 can be quite small, pref.- erably consuming not over lO watts and, therefore, it is permissible to locate this motor within the refrigerated space. Some of the waste heat from the motor 43 may be utilized in maintaining the temperature of the butter compartment, as will later be explained.

In Figure 2, it is seen that the lower left corner of the upper tank 26 is rounded and that the bottom of the tank 4 slants downward to the left side of the ice maker tank 1?.. This provides for conducting the moisture which condenses ou the side and bottom of the ice bunker over to a side wall of the ice-maker tank from which it drops into the pan 54 which, therefore, can be made narrower than would be otherwise required. This pan is preferably drained to the rear corner of the liner of the food space and the water conducted outside of the refrigerated space to be re-evaporated to room atmosphere as disclosed in my @Spending patent application Serial No. 178,498 filed August 9, 1950, now Patent No. 2,765,633.

Referring now to Figure 3, we are looking down on the top of the ice bunker 26. The butter compartment 56 is located beside andv preferably separated from the ice bunker 26. At its front, it is provided with a door 58 for access and at its rear is provided with a thermostatically controlled shutter 60 which opens in response to a drop of temperature within the butter compartment to allow warm air and radiant heat from the motor 48 to enter the butter compartment for the purpose of maintaining its temperature. As the butter compartment rises to the desired temperature, the thermostat 62 moves the shutter in a closing direction to reduce the heat input to the butter compartment.

The belt 18 and the vanes 16 may be molded or vulcanized together in one piece using a combination of material or one rubber-like material. It is preferred that the vanes 16 be flexible or exibly mounted upon the belt so as to prevent damage in the event that an extra large disk of ice wedges between a vane and the rear wall 34 of the ice-maker tank in the position indicated in Figure l by the ice disk 14".

A-t the top of the rear wall 34 or on the sides 30 of the vertical chute 28 a curved shield 64 is provided as an extension of one or two walls to prevent the ice disks from rolling off from the ends of the vanes 16 as they yapproach their top position. The vane then pushes the ice disk off the top of the pulley with sutcient force to carry it over the wall 32 into the ice bunker. In the event that an ice disk should lodge between the belt and the top edge of the wall 32, `as indicated by 14" in Figure l, the vane 16 which carried the ice disk up will push the ice disk over the top of the wall 32 so that it falls into the ice bunker.

In order to make the float valve 44 readily accessible, I prefer to use a two-piece cover for the ice-maker tank 12, as shown in Figure 1. The shield 36 fits into the tank 12 and provides an angular wall 66 which aids in guiding ice toward the elevator. This shield is readily removable by merely lifting it out after removing ice from the bunker 26. Upon removal of the shield 36 the somewhat similar float cover 38 may be removed by sliding it rearwardly, tilting and lifting it out along with the oat 42, its lever `arm 68 and its pivot pin 70. This provides access to the valve 44 which is preferably threaded int-o a fitting such as 72 and is readily removable therefrom by the use of a socket wrench. The valve 44 is similar to an automobile tire valve, having a removable core or valve guts. Such valves are well-known as tank valves and lare commonly provided with 1/s male pipe threads.

In Figure 2, the evaporator 74 is provided with ns 76 and is open to circulation of air from the food storage space of the refrigerator for the purpose of cooling the same. The arrows indicate such circulation and the upper one indicates flow of air into the top of the nned evaporator 74, there being an opening or openings provided in the sheet metal wall 78 for that purpose. The evaporator 74 may be operated intermittently during periods when the ice maker evaporator is idle, the two evaporators may operate at the same time or they may each operate under its own control as required to make ice and to maintain the desired temperature of cabinet air.

It will be obvious that a considerable amount of cooling of 4cabinet air is obtained by normal gravity circulation of air over the exposed surfaces of the ice-maker tank 12 and the ice bunker 26 as well as by contact of the ice-maker proportion to the amount of light.

evaporator 80 during both its active and defrosting periods which are controlled to regulate the size of ice disks made.

'Ihe controls described later herein and illustrated by Figure 6 provide for so proportioning this operation of evaporators 74 and 80 that cabinet air temperature is maintained within the desired limits and ice production is regulated to maintain the desired supply in the bunker 26.

The butter compartment 56 is provided with a glass bottom 82 supported by the two side members 84 which are tied together by two or more cross members such as 86. This compartment is closed at the front by the door S and at the rear abuts the rear liner of the cabinet, so that no rear wall is required. AThere is, h-owever, a partial dividing wall 88 arranged to separate the butter compartment 56 from the rear compartment 90 in which is located the lamp 92. This Wall stops short of the top and bottom of the :butter compartment so that the heat produced by ,the lamp causes warm air to ow forwardly over the partition member 88 and to return below it. In conventional refrigerators it has been customary to provide such a lamp with a switch arranged to close when the refrigerator door is opened. Such a switch is located within the housing 94 and actuated by the push rod 96 which extends forward :so tha-t the switch is opened whenever the door is closed. In addition to this switch, I propose to use a second switch connected in parallel with it and enclosed in the same housing 94. This second switch is of the thermostatic type and arranged to close in response to a drop of air temperature within the compartment 56 and to re-open in response to a rise of this temperature. Such switches have previously been employed to actuate heating elements for the purpose of maintaining the desired temperature in a butter compartment of a refrigerator, but in this case, I propose to use the lamp 92 as a heating element as wellfas for the purpose of illumination. In order that the thermostatic switch need not carry a heavy current, I propose to include a resistance coil in series with this thermostatic switch and the lamp, so that when the lamp is lighted for the purpose of producing heat, it operates at a lower-than-normal voltage, hence produces little light but a high percentage of heat in The resistance element thus connected also provides heat for the butter compartment 56 and acts to hasten the operation of the thermostatic switch which is enclosed n the same housing with it, thus resulting in the effect of an anticipating thermostat. The thermostatic switch within 94 is adjustable from the inside of the butter compartment by means of the knob 98 which carries a pointer 100 to indicate its position. v

Another method of supplying heat to the butter compartment is illustrated in Figures 2 and 3, where the bimetal thermostat 62 actuates the connecting rod 102 and thereby the louver vanes 60. These `vanes 'move to the open position as shown in Figure 2 when the bimetal element 62 drops to the minimum temperature desired within the butter compartment, thus allowing heat from the motor 48 to be transferred by radiation and convection to the compartment 90 'and thence to the butter compartment 56 by convection. The thermostat 62 is adjustable by means of the pointer 104. It will be seen that I have provided three -sources of heat for the butter compartment 56, but it is not proposed that all three be used in the same model. Normally, there will be two sources of heat used such as the lamp and the resistance coil, or the lamp and the heat from the motor 48, hence there will be only one thermostat employed and only one dial for its adjustment.

When the lamp is connected in series with the resistance coil, 'it is periodically energized even when the door of the refrigerator is closed. This aids in keeping the lamp base, its electrical connections, and the thermostatic switch dry. It will be noted that the position of the lamp within a somewhat warmer compartment prevents the collection of dew on the lamp and its base as well as on the connecting wires and the operating switch. The lamps location above" the glassA 82 protects it and avoids the usual inter'- ference with the cleaning of the refrigerators interior.

It is also within the scope of my invention to keep the lamp' in the position shown and connect it only with the door-operated switch so that it operates in the usual manner, Ibut it and its switch are enclosed within this warmer compartment where both are readily accessible for service and less servicing is required because both are kept dry. In this case the thermostatic switch -adjusted by the knob 98 would be independent of the lamp circuit and in series only with the resistance coil which provides all of the heat for the butter compartment except the incidental heat from the lamp 92, which is produced only while the refrigerator door is open.

Another arrangement is to keep the lamp and its switch independent as above described, eliminating the knob 98, its switch and the resistance coil but using the thermostatically controlled shutter whereby heat -is admitted to the compartment from the motor 48. This retains the dry location of the lamp and its switch and provides the additional heat without use of electrical current by merely opening the louvers 60 when required to maintain the desired temperature within the butter compartment.

The. lamp bulb may be removed by sliding the glass 82 forward and whatever switch or thermostat is used can be readily removed for servicing along with the supporting wall 88, `which is preferably made of thermal insulating material.

Figure 4 shows a modiedform of the apparatus seen in the rst three tigures, differing mainly in the arrangement of parts. The elevator belt 18' is arranged at an angle instead of vertically so that the round -ice blocks 14 are caused to roll up the inclined track formed by the wires instead of being lifted vertically as shown in Figure l. This elevator delivers the blocks of ice to the ice bunker 112 which is separate from the ice-maker tank instead of being an upward extension of it as shown in Figures l and 2. The motor 48', which includes gear reduction to drive the belt 18 of Figure 4, is located outside the refrigerated space as shown in Figure 5 instead of being located inside. of the refrigerated space as shown in Figures 2 and 3. The butter compartment 56 is therefore heated by an electrical resistance element under thermostatic control as described in connection with the control assembly 94 of Figures 2 and 3, though this motor could optionallyA be located inside the refrigerated space adjacent to the butter compartment 56 for the purpose of heating it if desired.

The ice-maker tank 12 is joined at its left and with the water tank 114 and the faucet 46 is connected with this water tank instead of being located on one end of the ice-maker tank. The ice-maker tank is located adjacent to and parallel with the inner side of the removable plug 116 back of the shelf 118 which is provided for the storage of tall bottles whereas in the arrangement of Figures 1, 2 and 3 such bottles would be placed on the shelf 118 at the left side of the ice-making apparatus.

Since the ice storage bunker 112 of Figure 4 is located at the same level as the ice-maker tank instead of above it as shown in Figures l land 2, provision is made for disposal of the water of meltage. This is done by means of the pump 120 which may be of a reciprocating type driven by an eccentric 122 (Fig. 5) on the shaft 52 which carries the pulley 20 and drives the belt 18. from ice meltage is returned to tank 12 or 114 by means of the tube 124. The ice bunker is provided with `a water-tight front to which the door is hinged at one-' half to two-thirds of the height of the ice bunker. This provides storage -space for the water resulting from ice meltage in the event of current failure or accidental stoppage of the refrigerating system. In Figures 4 and 5, the water in the ice-maker tank is stirred by the vanes 1'6 of the belt as previously explained in connection with Figure 1. Thebelt is not, however, required to vlift the 4ice disksfrom the water but merely to roll them up i Water resulting I,

on` the ramp formed` by the wires, 11.0, under guidance of the side.wire`s.126. These wires may all be formed by one continuous wire which also forms two vertical portions 128 and two angular legs 130 which hold the formed wire element in position `and guide the ice disks upwardly into the path of the vanes 16 after the ice is released from the walls of the tank. The two ends of the formed wire are bent upwardly at 132 to be retained back of the downwardly extending lip 134 of the spout-like extension 136 of the tank 114. Assembly of the wire element to the tank is 'accomplished by hooking the ends 132 baci: of the lip 134 and then swinging the wire member downwardly through the adjacent corner of the ice-maker tank until the vertical legs 128 snap into position as shown in Figure 4. Removal isaccomplished by squeezing the two legs 128 together so that` the wire willagain pass through the` corner of theice-m-aker tank` i The oat 42 is pivoted at 70 tothe inverted U-shaped member 138 which ts snugly over the end of the icc maker tank so that when the float 42 fallsl as a result of a drop of water level in the ice-maker tank the arm 68 contacts the stem of the valve 44 to adm-it additional water from the supply tube 140.` A wall member 142, which is preferably removable, is provided to prevent any pieces of ice from floating into the water tank 114. Ice disks are free to float upward when released since the icemaker tank 12' is slightly wider at its top than at its bottom as is the similar tank 12 seen in Figure 2. This ice may float directly into the path of the vanes 16 of the belt 18 or they may be guided into suchcontact by the angular wire legs 130 or by the shield 144 which protects the float 42.

ln Figures 4 and 5 as well `as in Figures l, 2 and 3, the oating disks of ice are lifted from thev water rnechanically rather than being floated out as in my copend ing application, Serial No. 50,101 filed September 20, 1948 or rolled out by a head of water accumulated back of an ice disk as shown in my copending application, Serial No. 174,944 filed July 20, 1950. This` eliminates the necessity for pumping overflow water back to the ice-maker tank. The pulley which drives the belt 18 or 18 could be driven at an` extremely slow speed and still move the belt rapidly enough to remove th ice blocks as fast as they are released, but it isproposed to drive this pulley at a somewhat, higher speed so that the vanes 16 will produce sufiicient agitation of the water in the icemaker tank to wash air bubbles frornthe surfaces of the iceV disks as they are forming and thus insure the production of clear ice. Since water is not being pumped through restricted passages nor lifted tc produce agitation andjtheniotorshaft requires no packing gland,

t the motor which drives kthe, belt 13er 1.8" can be considerablyA smaller. than the motor required to operate Va pump whichproduees enough flow to wash the air bubbles from the i'ceand., to cause the ice to float out of the tank in which it isrnade.

Figure 6 shows diagrammatically a system suitable for use in connection with` the previous views and. including a freezer evaporator 14-8 which is employed to cool a frozen food compartment as is the evaporator 20 of my` copending United States patent application Serial No. 74,528 filed February 24, 1949,'now Patent.l\.l.o..2,709,343 or evaporator 88 of my copending United` States` patent applicationtSerial No. 178,498 iiled.A1.1gustQ,t1950. This evaporator includes a header 150 and is selectively cooled under control of solenoid valve `152 and` thermostatic switch 154` which responds to temperature changes of a bulb` located adjacent to evaporator 148.

The solenoid of valve 152 is energized while motorcompressor unit operates to cool evaporators Sil and' 74. During this period refrigerant vapor compressed by the motor-compressor unit 156 is delivered to the condenser 158 and liquid accumulating therein ows into the receiver 159` and thence through the tube 160 to the ex` pansion valvev 161 which is` of the thermostatic type and has its bulb 162l adjustedly supported, as will be explained later. l

Liquid` refrigerant leaves the expansion valve 161 through the tube 163 which extends into the tube 164. past the point at which tube 164 is joined by tube 166. This produces a jet effect which induces flow through the tube 166 in the direction indicated by the arrow. A portion of the liquid refrigerant evaporates in the evaporator 30, seen in previous figures as part of the ice maker.

Vapor and unevaporated liquid refrigerant ow from the evaporator into the evaporator 74, which is arranged to cool air within the refrigerator cabinet and is preferably provided with extended surface as shown in Figure 2. Refrigerant vapor leaves evaporator 74 through the tube 16B while any unevaporated liquid refrigerant 'hing the top of evaporator 74 flows through the tube 16o into the tube 164 and recirculates until evaporated. At the time evaporators 89 and 7 4 are active the solenoid valve 152 is lifted so that refrigerant vapor flows from thc tube 168 into the main suction tube 170, which leads back into the low pressure casing of the motor-compressor unit 156.

This cycle of operation is Linder control of the therrno-v have built up in the evaporators 74 and 80 to close theV expansion valve 161. Liquidrefrigcrant therefore flows from the tube through the branch liquid tube 174 to the expansion valve 17 6', which feeds the freezer evaporator 14S. 1453 through the suction tube 178 which connects with the header 156 and is now open at the valve 152-.for the flow of refrigerant vapor from thetube 178 to the main` suction tube 170 and thence back to the unit 156.

l'n the event that thermostatic switch 172 recloscs bcfore the switch 154 reopens', the cooling effect will shift back to the evaporators 80 and 74, due to the energizing of the solenoid and consequent lifting of the valve mcmber of 152. The main food compartment of the ref frigerator is thus cooled and ice is formed until the switch 172 reopens, whereupon cooling of the evaporator 148 continues until the freezer air temperature falls to the cutout point of the switch 154, whereupon the unit 156 stops. l

An additional switch is provided for defrosting of the evaporator 148. This may be a double poie, double throw switch, which for convenience and clarity is here shown as 180A and 180B, with the two blades or movable members shown in solid lines and their alternative positions shown by dotted lines. As indicated by solid lines the switch 130 is in its normal position which prcvails at all times except when the heating element 182 is to be energized for the purpose of defrosting the freezer evaporator 148.

It will be seen that when the two blades of the switch` 180 are Isimultaneously moved to their dotted positions the blade of 180A connects one sido of the line with one able contact elements to the positions shown by dotted lines will complete the circuits through the solenoid of i 152 and through the heating coil of 182. 'lhiscauses the valve of 152` to`lift, 'closing Athe outlet oftube 178 v whiletat the same time the heater 182 causes evaporation Vaporized refrigerant leaves the evaporator` of liquid refrigerant in the header V150 of evaporator 148. Such evaporation of refrigerant causes condensation of refrigerant vapor within the tubes or passages of the evaporator 148 and within the upper portion of the header 150, thus melting any frost or ice that may have accumulated on these parts or extended surfaces thereof.

The outlet of tube 178 is stopped by a valve held closed' magnetically, vhence this valve acts as a pressure relief valve. In the event of excessive pressure developing within the evaporator 148 refrigerant vapor is allowed to pass into the tube 170 and thence to the low pressure side of the unit 156, which has ample internal volume to receive and hold all of the refrigerant vapor that may be passed by the valve 152 during the defrosting of evaporator 148. I

lThe switch 180 may be actuated either manually or automatically, but it is preferred that at least the termination of the defrosting operation be automatic, as disclosed in my copending patent application Serial No. 178,498 above mentioned, which discloses means for accomplish- `ing automatic starting as well as stopping of the defrosting operation.

Figure 6 also shows connections for supplying-electrical energy to the motor 48 and to the lamp switch and butter compartment heater 94 which are seen in v Figures 2 and 3. It will be noted that the thermostatic :switch 172 is shown with two bulbs instead of the usual .single bulb. One of these bulbs is adjustably located yadjacent to an ice making area and the other is located so as to be responsive to changes in the quantity -of ice in storage under the additional inuence of changes in air temperature within the refrigerator, as disclosed in my copending application, Serial No. 178,498 and illus-` trated by bulb positionsl in Figure 6 thereof. This arrangement causes the switch 172 to regulate the ice making cycles to produce ice disks of the desired size and to maintain the desired quantity of ice in storage, this quantity of ice -being greater when the air temperature of the main food compartment of the refrigerator is near its high limit than when the air temperature is near its low limit.

In addition to this previously disclosed method of control, the present invention provides additional means for proportioning the cooling effects produced by the ce maker evaporator 80 and the cabinet air cooling evaporator 74. The expansion valve 161, being of the thermostatic type, is urged in its closing direction by a reduction of temperature of the bulb 162. In the event that the bulb 162 is at a higher-than-normal temperature, the expansion valve 161 maintains a higher-than-normal operating pressure within the evaporators 80 and 74. lt

will be noted that the bulb 162 is associated with the outlet of evaporator 74, but also has a considerable portion of its length exposed to air temperatures above its contactwith the tube 168. The bulb is adjustably supported so that more or less of its length can be exposed to cabinet air temperature. An upward adjustment of the bulb may raise the liquid level within the bulb above the uppermost contact between the bulb and its support or with the tube 168.

This provides for increasing the ow of liquid refrigerant through the expansion valver161 when the air ternperature within the refrigerator is higher than normal. This increased ow of liquidl causes evaporator 80 to operate at a higher-than-normal evaporating temperature, thus slowing down the formation of ice. At the same time the greater supply of liquid causesmore of the evaporator 74 to be cooled and this cooling is prolonged due to the slower formation of ice and consequent longer running' period for each batch of ice frozen.

While the bulb 162 is closely enough associated with the tube 168 to insure against frost-back, the expansion valve 161 is set at a considerably higher superheat than is customary in thermostatic expansion valves, thus the expansion valve 161 is controlled mainly by vair temperature and only Vin emergency by suction tube temperature to prevent Vfrost-back. The result is that evaporator 74y may have only its lower loops frosted during normal operation lof the refrigerator, but in the event of frequent door openings, an excessively high ambientv temperature, or the placing of an unusual amount of warm food in the main food compartment of the refrigerator, the evaporator 74 will be supplied with more liquid and be frosted nearly to its top. Since the length of each running period depends upon the formation ofice and the evaporator is under this condition operating at a higher pressure than usual, the formation of ice is retarded and the running period prolonged while the evaporator 74 presents a greater cooled area to the cabinet air.

During idle periods of the system, that is when the motor-compressor unit 156 is idle, as well as when the system is actively cooling the freezer evaporator 148, the evaporators 74 and 80 are isolated from the balance of the system by the valve 152, which closes the outlet of tube 168, and by the expansion valve 161, which'does not allow flow in a reverse direction. Thererwill always be some liquid refrigerant trapped within these two evaporators at thetime the switch 172 opens and the solenoid is thereby de-energized. TheA cross-over tube 166 allows vapor from the evaporator 74 to ow into the upper portion of the evaporator 80 where it will condense due to the fact that evaporator 80 is in intimate thermal contact with the ice-maker tank 12 while the evaporator 74 is not only in air but is provided with ns, as seen in Figure 2, so that it approaches more closely to cabinet air temperatures, causing liquid refrigerant to evaporate in '74 under the same pressure at which it condenses in the evaporator 80, which Anow acts as the eondsenser of Ya secondary or constant pressure refrigerating system, transferring heat from cabinet air to the ice-maker tank 12.

Figure 6 illustrates the method of controlling cabinet air temperature in the main food space, which must be held above the freezing point and is preferably held below 40 F. A considerable part of the cooling effect required is obtained by air contact with external surface of the ice bunker 26, the ice-maker tank 12 and the ice-maker evaporator 80, but a variable amount of additional cool ing effect is required to hold the air temperature within the main foodv storage space below the desired top limit which may be y40 F. or lower. This variable cooling effect is supplied by the evaporator 74. This evaporator vdoes some cooling of air each time the ice-maker evaporator 80 is cooled for the purpose of making ice.

Evaporator 80 is undercontrol of thermostatic switch `172 which has two bulbs 173 and 173 connected with it, bulb 173 being located relative to an ice-making area and bulb 173 relative to the height of the maximum ice supply in the storage compartment 26. Equivalent locations of the two bulbs connected with one thermostatic switch are shown at 44 and 138 in Figure 6 of my -copending U. S. patent application Serial No. 178,498,

led August'9, 1950. Bulb 173 regulates ice-making periods by stopping the compressor when a given piece of ice has grown to the desired size and by starting the compressor when the ice has melted free from the surface on which it was frozen and floated. Bulb 173' which is located in the ice bunker, takes no part in the control until the icel supply has accumulated to slightly above the level of the bulb, thus cooling bulb 173' and causing the liquid portion of the volatile charge of the thermostatic switch 172 to collect in this bulb, which is now` colder than bulb 173 associated with the ice-making area.

Each of these bulbs is affected to some extent by a rise of cabinet air temperature, in the direction'of hastening the rstarting of kan Vice-making cycle and increasing running time, which effect tends to cause more coolingof cabinet air when the cabinet air `temperature is higher than normal, but I have in the present application shownthe ice-making cyclesfandlby varying the amount of cool ing done by the finned evaporator 74. It will vbe obvious that when evaporator `80 is cooled to, a very low temperature and aurelatively vsmall amount. of liquid refrigerant is allowed to flow into evaporator 74 ice will be formed rapidly and the evaporator 74 will do only a small amount of cooling of cabinet air. On the other hand when evapof rator 80 is operated at a higher temperature, with a greater excess of liquid refrigerant flowing from it into evaporator 74, more time will be required in forming ice disks of the desired size and during this longer-period of operation a larger portion-of the evaporator 74 will be actively cooled by the evaporation of refrigerant.

In order to regulate the removal of heat from cabinet air I employ the thermostatic expansion valve 161, which is responsive to variations of low side pressure and also to variations in temperature ofthe bulb 162. Such bulbs are commonly placed in heat exchange relationship with the outlet of an evaporator and the valve is designed to maintain approximately the desired temperature at the evaporator outlet. It is common practice to identify the setting of such valves in terms of superhea of refrigerant vapor at the point of bulb attachment to the evaporator outlet tube. They are usedY to insure cooling of substantially the entire evaporator from start to finish of its active period. Inv the present case the bulb 162 has only a slight'contact with the tube 168 leading from.

evaporator 74 but has a considerable portion of its area exposed to thecirculation of warm air approaching the top of the ns 76 of evaporator 74. i

In addition I make the valve 161 responsive to temperature changes ofbulb 162 at higher temperatures than usual. In other words, the valve 161. is set at a muchl higher superheat than usual. When the bulb 162 is the formation of ice and the running period ends in, re-` spouse to the building up of one of the ice `disks 14 to the maximum size established by the location of the bulb of thermostat 172 which contacts the tank 12 adjacent to one of the ice-making areas thereof.

In effect the bulb 162 replaces the usual bulb of al thermostatic switch in the control of cabinet air temperature. When cabinet air. temperature is high this bulb causes evaporator 74 to be more fully cooled and to` be cooled for longer operating periods, thus pulling the air` temperature down to normal for the purpose of holdingV it within the desired limits. The adjustment of bulb 162 relative to tube 168 to decrease the thermal conductivity between these parts has the'effect of a colder setting of the ordinary manual adjustment of a thermostatswitch which responds to air temperature. within the cabinet. The knob 188, Fig. 2, may be arranged to move bulb 162 for this purpose.

Another effect obtained by the system illustrated in Fig. 6, as applied to any of the other figures and particularly to Figs. 1, 2 and 3, is that in the event of a prolonged idle period, such as might be caused by failure of the source of current, the reserve cooling effect of ice and cold water in the tank 12 becomes effective in cooling i cabinet air, not only by exposed surfaces of the tank and of the evaporator 80, but by means of evaporator 74 which acts as a secondary evaporator during idle periods of the system with evaporator 80 serving as the secondary condenser. This hold-over effect can be greatly increased by raising the water level 24 so that at least the lower portion of the ice stored in ice bunker 26 is below the water level. within the tank 12 is normally maintained between 32 F. and 39.2 F., and is consequently within the range of reverse thermal expansion of water, the 32 water in contact with the ice will be more dense than the water Vin the tank 12 when the latter rises to 40 F. Thus there cooled'to say 35 F. the evaporator 80 may be operating v F. with substantially all of the liquid refrigerant evaporating in the evaporator 80 and very little of it in evaporator 74. This condition would be stated as opa erating at a superhea of 25 F. If the valve really maintained a 25 F. superheat and bulb 162 was increased from a temperature of 35 to a temperature of 40 the evaporating temperature would rise from 10 F. to F., thus slowing down the formation of ice and allowing more liquid refrigerant to ow into the evapo rator 74. Ilmay, however, prefer to design the valve 161 so that the rise of temperature of bulb 162 increases the tiow` of liquid.- refrigerant so that evaporator 80 operates at say F. and a still greater proportion of the liquid refrigerant tiowsinto evaporator 74. In other words, the expansion Valve 161 may operate at a diminishing superheat as the temperature of its bulb 162 rises. This ar rangement of the bulb 162 so as to be mainly responsive to temperature of the warmer cabinet air approaching the top of the tins 76 modifies the cooling of evaporator 74 so that only one or two of its lower loops may-be cooled by evaporation of refrigerant when cabinet air temperature is low (say F.) and substantially all of evaporator 74 is cooledwhen the air temperature rises to say F.

It will be obvious that under the latter condition, the bulb 162 will begin to be cooled by the tube 168 through which colder vaporis now flowing, thus the slight thermal contact between bulb V162 andptube 168 is sufficient to insure against frost-back from evaporator 74, even though the air temperature may be quite high, as in the case of pulling down a warm cabinet.

In addition to varying the refrigerated area of evaporator 74fto `maintain the desired airtemperature it will be seen that each running period of the connected evaporators 74 and 80 will be longer when vthey are operating at afhigher` evaporating pressure, since thisv slows down Figure 6 so that-this motor operates during ice freezing periods only. In the latter case it is assumed that the tank 12 will have ample volume above` its'ice-making areas for released pieces of ice to oat out of contact with such areas or that upon starting of motor 48 ice will be removed rapidly enough to insure against any of the floating pieces of ice` being trapped by freezing to the wall` areas which evaporator is starting to cool.

Figure 6 also shows the wiring to the assembly 94 which includes a heating element and `a thermostatic switch for connecting the heating element of 94 in series with lamp 92 when the temperature of butter compartment 56 falls and opening this circuit when the lbutter compartment has risen to the desired high limit of temperature. The lamp 92 lights under full line voltage as usual when the door-operated switch is closed, this switch being connected to short out the heating element of 94.

I claim:

The method of cooling a body of air and holding it within a non-freezing temperature range which consists of evaporating a liquid portion of a volatile fluid in heat exchange Vwith said air after a first portion of said fluid has been evaporated at a sub-freezing temperature for the purpose of freezing a substance, regulating the rate of flow of said liquid and thereby the quantity per unit of time evaporated to cool said air in accordance with temperature changes of said air, stopping the freezing of said substance at a preselected stage thereof, and while said freezing is thus stopped employing said substance tot i absorb heat from and thereby condense a vaporportio of said tiuid for the purpose of supplying said fluid in While it is true that the water liquid phase to evaporate and thereby continue cooling said air while a frozen portion of said substance melts free from the surface upon which it was frozen.

References Cited in the file of this patent UNITED STATES PATENTS Kalischer July 7, 1931 Tamm July 10, 1934 Smith Mar. 9, 1937 Arp Apr. 20, 1937 ,Wussow Oct. 18, 1938 Shoemaker Oct. 25, 1938 Muy Jan. 31, 1939 Wussow Nov. 12, 1940 15 Cooper July 8, 1941 Gaston Oct. 14, 1941 King May 12, 1942 Siedle Sept. 29, 1942 14 Cocanour Nov. 2, 1943 Whitney Feb. 1, 1944 Wild Nov. 21, 1944 Wild May 8, 1945 Berry May 14, 1946 Erickson Feb. 1, 1949 Schaberg Jan. 10, 1950 Leeson Apr. 17, 1951 Erickson Jan. 22, 1952 Braswell Mar. 25, 1952 Lee May 6, 1952 Nitsch May 20, 1952 Pownall May 27, 1952 Bixler Dec. 23, 1952 Eck Nov. 10, 1953 Jones Jan. 19, 1954 Shoemaker Feb. 2, 1954 Lindenberg Dec. 14, 1954 

